A wide variety of processes use radial flow reactors to provide for contact between a fluid and a solid. The solid usually comprises a catalytic material on which the fluid reacts to form a product. The processes cover a range of processes, including hydrocarbon conversion, gas treatment, and adsorption for separation.
Radial flow reactors are constructed such that the reactor has an annular structure and that there are annular distribution and collection devices. The devices for distribution and collection typically incorporate some type of screened or porous surface. The screened surface is for holding catalyst beds in place and for aiding in the distribution of pressure over the surface of the reactor to facilitate radial flow through the reactor bed. The screen is a mesh, either wire or other material, or a punched plate. For either a fixed bed or moving bed, the screen or mesh provides a barrier to prevent the loss of solid catalyst particles while allowing fluid to flow through the bed. In a moving bed, solid catalyst particles are added at the top and flow through the apparatus and are removed at the bottom, while passing through a screened-in enclosure that permits the flow of fluid over the catalyst. In a fixed bed, the catalyst, or adsorbent, is loaded into a bed between screens, or other retention devices, and the screens allow fluid to flow over the catalyst while holding the catalyst in place. The screen is preferably constructed of a non-reactive material, but in reality, the screen often undergoes some reaction through corrosion and/or erosion, and over time problems arise from the corroded or eroded screen or mesh. For example, as a result of use, the screen includes carbon deposits and scale that clog the pores of the screen and reduce the performance of the reactor.
In order to remove deposits and other material on the screens, conventional cleaning processes remove the screens from the reactor and remove the foulants from the screens. Specifically, when it is necessary to clean the reactor screens, the reactor is shut down and the catalyst is removed from the reactor. After removing the catalyst from the reactor, the screens are dissembled and removed from the reactor. Then, once removed, the screens are cleaned to remove any foulants. Once they have been cleaned, the screens are reassembled inside of the reactor. Accordingly, as will be appreciated, such cleaning methods are both time consuming and costly.
Therefore, there is a need for effective and efficient processes for cleaning the surfaces of the retaining screens that reduce the amount of time required to clean the surfaces of the retaining screens. Furthermore, it would be desirable to have one or more cleaning processes in which the screens remain in the reactor for the entire cleaning process.